For formation of a copper film on electrically insulating articles, the nonelectrolytic plating method, the vapor deposition method, the press adhesion method, the method using an adhesive, and so forth are used.
The nonelectrolytic plating method is most commonly used and is excellent, but has disadvantages in that a special pretreatment depending on the article is usually needed, a material modified for plating is needed depending on the type thereof, and the process is complicated. For example, when an article of thermosetting resin or thermoplastic resin is used, a method in which in order to omit or simplify the pretreatment, an article of a composition with a diene-based rubber and the like previously compounded thereto is used, is known. In this method, the performance of the resin itself is often deteriorated. In the case of an article in which a filler, e.g., glass fiber, is compounded, if the filler is exposed to the surface, good adhesion cannot be obtained.
The vapor deposition method needs a special equipment for vapor deposition, and thus a large-sized article is difficult to produce. Furthermore, the method needs a pretreatment for increasing adhesive properties depending on the type of the article.
The press adhesion method and the method using an adhesive are sometimes used, but have disadvantages in that press adhesion is impossible, the form of molding is limited, and when an adhesive is used, the adhesive layer is increased and the physical properties of the adhesive layer deteriorate the physical properties of the article.